Firing zone limiting apparatus

ABSTRACT

A FIRING ZONE LIMITING APPARTUS FOR A LATERALLY AND VERTICALLY ADJUSTABLE WEAPON WHICH IS PROVIDED WITH LATERAL ANGLE AND ELEVATION ANGLE CODERS BY MEANS OF WHICH THE CONTOURS OF BLOCKED AREAS CAN BE FED INTO A STORE OF AN ELECTRONIC CONTROL SYSTEM WHICH CONTROLLS THE ACTION OF THE FIRING MAGNET OF THE WEAPON.

Nov. 9, 1971 G. MINDEL 3,618,456

FIRING ZONE LIMITING APPARATUS Filed Sept. 2, 1969 5 Sheets-Shoot 1 "1 I "I "I1 16 1" Nov. 9, 1971 s. MINDEL FIRING ZONE LIMITING APPARATUS L5 Sheets-Shoot 3 Filed Sept. 3, 1969 United States Patent 3,618,456 FIRING ZONE LIMITING APPARATUS Gunter Mindel, Dusseldorf, Germany, assignor to Rheiumetall G.m.b.H., Dusseldorf, Germany Filed Sept. 2, 1969, Ser. No. 854,545 Claims priority, application Germany, Sept. 12, 1968, P 17 28 222.3 Int. Cl. F41d 11/02 US. Cl. 89-434 7 Claims ABSTRACT OF THE DISCLOSURE A firing zone limiting apparatus for a laterally and vertically adjustable weapon which is provided with lateral angle and elevation angle coders by means of which the contours of blocked areas can be fed into a store of an electronic control system which controlls the action of the firing magnet of the weapon.

This invention relates to a firing zone limiting apparatus for a laterally and vertically adjustable weapon, more especially for machine guns, equipped with a firing magnet.

Mechanical firing zone limiting mechanisms are already known. They have however the disadvantages that the adjustment and variation is very time-consuming.

It is an object of this invention to provide an improved firing zone limiting apparatus which obviates these disadvantages. According to the present invention this problem is solved by an electronic control system controlling the action of the firing magnet and by lateral angle and elevation angle coders disposed on the weapon, by means of which coders the contours of the blocked areas may be fed into a store or memory of the electronic control system and the store may be interrogated. The firing zone limiting apparatus constructed according to the invention affords the advantage that the contours of the blocked firing areas may be changed in simple manner and rapidly fed into the electronic control system so that the weapon is completely operational again very quickly after a change of location.

Lateral and elevation angles are measured with electromechanical angle pick-up means on the weapon and processed in the electronic control system. These angles may be measured in analog form, for example with function generators or potentiometers, or in digital form, for example in absolute digital form with angle coders or in incremental form, with angle step generators. Likewise, the following electronic store may be analog (with transfiuxors, memistors, potentiometers) or digital (with annular core storage matrices, transfluxor matrices or transfluxor shift registers). It is also possible to have hybrid circuits, with interposition of analog-digital or digital-analog converters. Rotary stores (drum stores, disc stores) are possible, but for high swivel velocities their access time will probably be too great. For all combinations, over each lateral angle range an associated elevation angle range in which firing is prevented must be measured and stored. In this manner it is possible to effectively protect objects, particularly within close range of the weapon.

The electronic system permits three operative states: erasure, storing, firing. After a change of location the angle combinations previously fed in are erased by a push button or a program switch with tip position. The gunner thereafter executes a complete revolution of 360 with the weapon and looking through the telescopic sight varies the elevation angle according to the contours of the objects to be protected. The duration of this storing or feed-in operation depends on the skill of the gunner. It may be about a minute. Simultaneously with the storing operation the gunner can allow for a safety margin round the contours based on values determined by experience; alternatively, this work may be left to a minicomputer which feeds corrections into the electronic system. It is possible either to feed correction values simultaneously into the store or to make them effective only on firing. The electronic firing zone limiting apparatus affords great advantages over all known mechanical or electromechanical methods. In addition to the reliability obtainable (due to the absence of mechanically moved parts within the control) the lateral angle-elevation angle combinations described may be stored or corrected in an extremely short time. Moreover, the action of the firing zone limiting apparatus may be interrupted at any time when required by the battle situation. This may for example be required in the case of a suddenly necessary ground action.

It is a further object of this invention to provide an electronic firing zone limiting apparatus which affords the possibility of following targets through blocked areas whilst keeping the firing button pushed down, so that full attention can be paid to aiming. This is particularly important with rapidly moving targets, above all low-flying aircraft. For example, if the gunner has a low-flying aircraft in the sight and is firing at this target with continuous fire, single-shot fire, controlled continuous fire (cadence fire) or with controlled fire bursts (rhythm fire) shooting is automatically interrupted as soon as the target passes into blocked areas (peculiarities of the terrain, buildings, friendly units in the vicinity, hightension lines). As soon as the target leaves the stored block areas again firing recommences automatically.

The firing zone limiting apparatus according to this invention uses as angle pick-up means, so called angle coders, i.e. angle pickup means for sensing the angle of rotation in digital absolute form. This provides a division of lateral angle and elevation angle into individual steps corresponding to the necessary resolution. It is convenient to use for storing the lateral angle-elevation angle combination a digital store, i.e. a core store matrix. The angle coder is coded in binary notation (l248) and is subdivided into 2 512 angular intervals per revolution. This gives a resolution of 360/5l2=0.7, corresponding to an accuracy of i0.35. The number of lateral angle increments gives the number of addresses for the core store, i.e., 512. A stored number, also referred to in the art of data processing as word, is to be found under each of these 512 addresses. If a resolution of 0.7 per interval is chosen for the elevation angle as well, and the range to be covered limited to 5 to +40", 2 :64 intervals are obtained. The word length is thus 6 bits. The total number of cores in the core store matrix is thus 512 6=3072.

The present concept enables the incorporation of socalled cut-outs (windows) into the firing zone limitation. Windows are areas above or below the contour initially fed into the apparatus in which firing is also blocked or possible. Examples are firing beneath a high tension line or blocking firing in the area of an obstructing barrage balloon. Such requirements means a correspondingly higher storage capacity.

Of particular importance is the compensation of the switching-off delay of the firing magnet. Starting from the command to stop fire, depending on the breech speed of the gun up to ms. can elapse. At a high swivel velocity firing could therefore take place in blocked areas. A dynamic minicomputer takes account of the lateral and vertical angular velocity of the weapon and determines a lead for the calling up of the store address. The minicomputer can also take account of ballistic data (wind velocity, V atmospheric pressure, etc.). These corrections are termed firing blocking in dependence on the aiming speed. If the objects to be protected are situated mainly in the vicinity of the weapon, a correction of the fed-in contour values may be dispensed with.

Some of the objects of this invention having been stated, other objects will appear as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a very diagrammatic illustration of a gun provided with the firing zone limiting apparatus according to the invention;

FIG. 2 shows a part of the terrain surrounding the gun with the contours defining the firing zone;

FIG. 3 is a block circuit diagram of the electronic control; and

FIG. 4 is a view of the control panel of the control unit.

The gun illustrated in FIG. 1 is denoted generally by 1 and constructed as a twin gun. The left gun is denoted by 2 and the right gun by 3'.

The twin gun is mounted on a cross carriage 4 for vertical and lateral adjustment. Arranged on the top carriage 6 is a firing pedal 8 which is electrically connected to the electronic system 12. The electronic system 12 is further connected to a lateral angle coder C, and an elevation angle coder C and to a firing magnet 14 for the right and left gun. The electronic system 12 is also electrically connected to the control unit 16. Finally, there is a connection between a rounds counter 18 constructed in the form of a magnetic proximity measuring head or proximity switch and the electronic system 12.

FIG. 2 shows a part of the terrain surrounding the gun with the contours 101 defining the firing zone 100. Disposed within the blocked zone 102 is an unblocked area or window 100'. Firing is not blocked in the window 100'. It is therefore possible to shoot at targets within the area of the window.

The control unit 16 comprises a program selector switch 20 having a Position:

E=for single-shot fire, D=continuous fire, K=for cadence-controlled single-shot fire Rh=for rhythm-controlled continuous fire.

The control unit 16 further comprises a cadence switch which may be set to cadences of 60120-240360480 rounds per minute.

Finally, the control unit 16 comprises a rhythm selector switch with which, if the programme selector switch 20 is set to the position Rh, 5-10-15-2025 rounds/ burst may be selected.

A gun selection switch on the control unit 16 allows selective firing of the left gun 2 in the switch position L, the right gun 3 in the switch position R or both guns when the switch 50 is in its middle position L-l-R.

A last-round blocking device 34 (FIG. 3) for interrupting firing for the purpose of reloading is actuated in each case via a limit switch on the gun. The blocking device 34 may be rendered inoperative via the switch 60 of the control unit 16. In the switch position I the blocking device 34 1s switched in, but in switch position II it is disconnected.

The ready-for-firing condition (with unactuated lastround blocking device and unblocked firing zone) is indicated separately for each gun on operating the switches 70 and 7 0' via control lamps 71 and 71' on the control unit. In the case of these switches 70 and 70' as well, the switch position I is the on position and the switch position II the off position. The control commands occurring 1n the various types of operation are processed in a purely electronic control stage or programmed logical circuit which is denoted by 24 in the block diagram according to FIG. 3. The corresponding firing magnet 14 is actuated with the switching commands of the control stage via a power stage or electronic output unit equipped with thyristors and denoted in FIG. 3 by 26. This power stage 26 comprises substantially 2 x 2 thyristors for switching the firing magnets on and off.

In the operative condition continuous firing the switching-on thyristor is rendered conductive for as long as the firing pedal 8 is operated. The gun then fires with the cadence fixed by the breech times thereof. In the operative state cadence-controlled single-shot fire the switching-on thyristor is rendered operative in the timing of the cadence set by means of the cadence control device 42 connected to the control stage 24. The cadence of the gun is thus determined by the setting of the switch 30. In the operative state Rh the burst set at the switch 40 is fired in each case; the number of rounds for a gun is counted via the rounds counter 18 on the cradle and supplied to the rounds number limiting device 44 connected to the control stage 24. During firing the firing pedal must be continuously operated; otherwise firing will be interrupted directly.

A core memory is used as memory 28. This affords several advantages, such as practically unlimited life, no maintenance, high working speed and no moving parts. In the case of a contour outline without windows" (firing zone cut-outs) the digital store must contain Z =m-ld(n) store cores. In this equation:

Z =the core number m=the number of addresses, i.e. the division of the lateral angle into 512 individual steps, whence m=5 12 n=the word length, i.e. the division of the angle of elevation from 5 to +45 into 64 individual steps, whence n=64 (ld=logarithm to the base 2, often denoted by log A core number of is thus obtained.

A core store matrix is used which contains 32 X 16 X 6: 5l2 6:3072 cores in a plane.

In the case of a contour outline with window the digital store must be able to store three different elevation angle values per lateral angle unit. Additional data must also be stored depending on whether the window is above or below the contour, and for example larger or smaller angles blocked. If it is assumed that an elevation angle plane intersects only one window in each case cores are necessary.

The control unit contains a selector switch with three positions (1) O for erasing (tip switch lockable) (2) S for storing (3) central position for firing.

Before storing all cores are brought to a neutral position by tipping the switch to position 0. The gunner then moves the gun through a complete turn of 360, beginning for example at a lateral angle of 0, continuously varying the angle of elevation according to the contours to be blocked. Mounted fixedly on the gun are an angle color 0, with 9 outputs for the lateral angle and an angle coder C, with 6 outputs for the elevation angle. A 7th output indicates when the maximum possible blocking range of 40 has been exceeded and renders the firing zone limiter ineffective. After electronic adaptation in the code converter 36 associated with the lateral angle coder C, an output signal is formed for each lateral angle, for example 010010011, which is the binary form of 147 and corresponds to 103". This signal is fed into the core store 28. The data from the elevation angle coder C, are also adapted in a code converter 38 and incorporated in binary code into the columns of the store. After one complete revolution an elevation angle interval beneath which firing is blocked is associated with each lateral angle interval. The duration of the storage operation corresponds to the time required for one revolution.

After feeding in the data, the selector switch 80 in the control unit 16 may be moved from its upper position store to its central position fire (not indicated in FIG. 4).

If during firing the gunner moves the gun into a region which is programmed in the memory as blocked, the electronic evaluating system supplies a blocking pulse to the firing unit which interrupts firing in about 40 ms. The lateral angle coder C, interrogates according to its instantaneous position an address of the memory. The number stored there is supplied in binary code to a digital comparator 32 where it is compared by subtraction with the binary number produced at that instant by the elevation angle coder. In another embodiment after digitalanalog conversion the difference is formed in a differential amplifier and the differential output voltage subsequently filtered, which corresponds to an interpolation dependent on angular velocity. If the difierential is negative or zero, a firing blocking pulse is generated. If the differential is positive, the gun is free to fire.

The electronic system 12 may include a ballistic minicomputer 46 shown in dashed line in FIG. 3 and connected to the control stage 24 and the comparator 32. This minicomputer can exert a correcting influence on the rest of the electronic system in order to provide a safety margin round the contours when feeding in the contours of the firing zone or when firing.

Of particular importance is the compensation of the switching-off delay of the firing magnet I14. Starting from the command to stop fire, depending on the breech speed of the gun up to 100 ms. can elapse. At a high swivel velocity firing could therefore take place in blocked areas. The minicomputer 46 may therefore be designed to take account of the lateral and vertical angular velocity of the gun to determine a lead for the calling up of the store address. The minicomputer can also take account of ballistic data (Wind velocity, V atmospheric pressure, etc.).

As shown in FIG. 3, the electronic system is connected via two terminals 52 and 54 to a current supply with a voltage of about 18 to 30 volts.

For the realization of the various electronic functions (logical basic functions, memory functions, etc.) integrated circuits are particularly advantageous. They are combined as subassemblies on unitary plug boards (printed circuits).

In the drawings and in the specification there have been set forth preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

What is claimed is:

1. In a firearm having barrel means for directing fired projectiles, carriage means mounting said barrel means for movement over a range of lateral and elevation angles, electrical firing magnet means for initiating firing of a projectile through said barrel means, and firing actuation means electrically interconnected with said magnet means and normally operable by a firearm operator for ener- 6 gizing said magnet means and firing a projectile, the combination therewith of means for limiting firing of projectiles into at least one predetermined zone otherwise normally within said range of angles, said zone limiting means comprising:

angle coder means operatively connected with said carriage means for encoding electrical signals indicative of the position of said barrel means within said range of angles, and

electronic control means electrically connected with said angle coder means for receiving encoded electrical signals therefrom and electrically interposed between said magnet means and said firing actuation means for precluding energization of said magnet means in the event said barrel means is positioned to direct fired projectiles into said predetermined zone, said electronic control means including programmable memory means for storing signals identifying said predetermined zone and accessible for retrieval of zone identifying electrical signals and further including comparator means for comparing said encoded electrical signals with said zone identifying signals.

2. The combination according to claim 1 wherein said programmable memory means comprises a matrix of magnetizable cores.

3. The combination according to claim 1 wherein said electronic control means further includes round sensing means for detecting the firing of projectiles by said firearm and rounds number limiting means operatively connected with said round sensing means and responsive thereto for controlling the number of projectiles fired in succession.

4. The combination according to claim 1 wherein said electronic control means further includes cadence control means for controlling the rate of fire in rounds per minute of projectiles fired by said firearm.

5. The combination according to claim 1 wherein said electronic control means further includes ballistic computer means for taking into account the ballistic characteristics of projectiles fired by said firearm in determining whether said barrel means is positioned to direct fired projectiles into said predetermined zone.

6. The combination according to claim 1 wherein said programmable memory means and said comparator means cooperate in permitting firing of said firearm into at least one window area within and surrounded by said predetermined zone.

7. The combination according to claim 1 wherein said angle coder means originate binary coded signals and further wherein said comparator means functions by comparison of binary coded signals.

References Cited BENJAMIN A. BORCHELT, Primary Examiner S. C. BENTLEY, Assistant Examiner Grundberg 89135 

